1. Field of the Invention
The present invention relates to a nonmagnetic substrate and to a magnetic head using the same, and more specifically, relates to a nonmagnetic substrate having excellent abrasion resistance and processibility and to a magnetic head using the same.
2. Description of the Related Art
A magnetic recording and replaying system, such as a video tape recorder (VTR) or a digital audio tape (DAT), which uses a magnetic tape as a recording medium is provided with a magnetic head for recording and replaying the signal on the magnetic tape. Additionally, a magnetic recording and reproducing system such as a hard disk drive (HDD) or a floppy disk drive (FDD) which uses a magnetic disk as a recording medium is provided with a magnetic head.
Among magnetic heads, an electromagnetic-induction type is predominantly used, which includes a magnetic core formed of a high permeability material and a member such as a coil that is wound around the magnetic core. Generally, in the magnetic head of the electromagnetic-induction type, two core halves, cut by machining from a bulk high permeability material, have been joined together to fabricate the magnetic core. However, with the recent tendency toward high-density recording, a narrower track width and a narrower gap width have been required for the magnetic head of the electromagnetic induction type.
In order to meet the demands described above, use of thin-film magnetic heads has been implemented. The thin-film magnetic head is fabricated by depositing a magnetic thin film having high permeability and a conductive material thin film on a nonmagnetic substrate such as a ceramic, and using a thin-film processing technique such as dry etching to form a magnetic core or a magnetic coil. Additionally, multilayer magnetic heads have been put to practical use. The multilayer magnetic head is fabricated by depositing magnetic thin films and insulating films in multiple layers on a nonmagnetic substrate to form magnetic core halves and joining magnetic core halves together.
In contrast, although only for replaying, magneto-resistive heads in which a magneto-resistive element thin film is formed on a nonmagnetic substrate are used mainly for HDD systems.
Also, in the HDD system, a magnetic head is mounted on the end of a nonmagnetic substrate block called a slider in order to lift the magnetic head so as to be nearly in contact with a hard disk.
As the nonmagnetic substrate for the thin-film magnetic head, the multilayer magnetic head, or the slider, MnO--NiO-based double oxide has been known, for example, as disclosed in Japanese Patent Laid-Open No. 62-22411. The double oxide disclosed has an NaCl crystal structure containing MnO as a major constituent, enabling improvement in processibility.
The MnO--NiO two-component double oxide, however, does not always have sufficient abrasion resistance to a thin-film-deposited tape which has been developed particularly as a high-density recording medium, in comparison with a ferrite single crystal. Therefore, the thin-film magnetic head or multilayer magnetic head having the MnO--NiO two component double oxide as a nonmagnetic substrate or guard material has a shorter life in comparison with a bulk head or an MIG head having the ferrite single crystal as a magnetic core material. The problem is noticeable when it is used, for example, in a low-temperature, high-humidity environment.